JP3301153B2 - Projection exposure apparatus, exposure method, and element manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus and an exposure method, and more particularly to a scanning projection exposure for manufacturing semiconductor integrated circuits and liquid crystal devices.

[0002]

2. Description of the Related Art Conventionally, many devices of this type have a function of correcting the image forming characteristics because the image forming characteristics must be maintained at a high level. Factors that cause the imaging characteristics to fluctuate include those that occur due to changes in the external environment such as atmospheric pressure and air temperature, and the fact that the projection optical system slightly absorbs the exposure light. With respect to changes in the environment, atmospheric pressure and the like are monitored by a sensor as disclosed in, for example, JP-A-61-183928, and corrections are made accordingly. Also, for the absorption of exposure light, for example,
As disclosed in JP-A-78454, a method is known in which light energy incident on a projection optical system is measured, and a change in an imaging characteristic caused by exposure light absorption is calculated based on the measured value to perform correction. ing. In this case, light energy incident on the projection optical system via the mask is detected by, for example, a photoelectric sensor provided on the substrate stage. Further, in the projection optical system, in addition to the projection exposure light energy incident from the mask side, there is also light energy reflected on the photosensitive substrate and incident again on the projection optical system. It causes the imaging characteristics of the system to change. On the other hand, for example,
As disclosed in Japanese Patent Application Laid-Open No. 183522, measurement is performed by providing a photoelectric sensor that receives reflected light from a photosensitive substrate via a projection optical system and a mask in an illumination optical system, and forms an image forming characteristic by the reflected light energy. There is a method of calculating the change of the total imaging characteristic in consideration of the change of the image. In this case, since there is a photoelectric sensor in the illumination optical system, reflected light from an optical member, a mask pattern, or the like enters the photoelectric sensor at the same time as reflected light from the substrate. Therefore, in this method, a plurality of reference reflection surfaces having different known reflectances are provided on the substrate stage,
Each output ratio of the photoelectric sensor with respect to these reference reflecting surfaces is determined in advance, and the reflectance (reflected intensity) of the photosensitive substrate is determined based on the ratio. As described above, since the reflected light from the mask pattern is superimposed on the reflected light from the photosensitive substrate, the sensor output of a plurality of reference reflecting surfaces is obtained every time the mask is replaced, or the measurement and registration are performed in advance. Is required.

Conventionally, the amount of change in imaging characteristics due to absorption of exposure light has been obtained and corrected by the above method.

[0004]

SUMMARY OF THE INVENTION The above-mentioned conventional method is as follows.
It has been developed on the premise of a method of projecting and exposing the entire mask onto the photosensitive substrate at one time (referred to as a collective exposure method or a full field method). However, in recent years, a method of illuminating a part of a pattern region on a mask in a slit shape and exposing the mask and the photosensitive substrate while moving each other, a so-called scan exposure method, has been developed. This method not only has the advantage that the area illuminating the mask is smaller than the one-shot exposure method, so that the amount of image distortion or the nonuniformity of the illuminance is small. There is an advantage that large-area exposure can be performed without restriction.

However, in the scanning exposure type exposure apparatus, the energy incident on the projection optical system is not constant and changes while the mask is scanned with the slit-shaped illumination light. This is because, for example, the area of the light-shielding portion (chrome layer in the pattern) provided on the mask differs according to the position of the slit illumination area on the mask, so that the amount of energy incident on the projection optical system during scan exposure differs. It is caused by

Further, the reflected light from the mask pattern also varies depending on the position of the mask, and the accuracy of detecting the amount of energy reflected on the photosensitive substrate and incident on the projection optical system is inevitably deteriorated in the conventional case. Will be. As described above, there is a problem that it is not possible to accurately obtain the amount of change in the imaging characteristics due to the absorption of exposure light and perform correction.

The present invention has been made in view of such conventional problems, and has as its object to provide a scanning exposure type projection exposure apparatus and method capable of favorably correcting the imaging characteristics. I do.

[0008]

An illumination optical system for guiding illumination light (IL) from a light source (1) to a mask (R) provided with a predetermined pattern and illuminating the mask with a predetermined illumination area. And a projection optical system (PL) for forming a pattern image of the mask on the photosensitive substrate (W) and a mask stage (RST) for holding the mask and moving the mask in a plane perpendicular to the optical axis (IX) of the projection optical system ) And image forming characteristic correcting means (30, 31, 32, 33,...) For correcting the image forming characteristics of the projection optical system.
40), the exposure of the entire circuit pattern is performed by relatively moving the mask and the illumination area. In the projection exposure apparatus, the illumination light incident on the projection optical system via the mask depends on the position of the mask. Input light intensity input means (101, 28, 41) for inputting the input light intensity, and an image forming characteristic calculating means (100) for calculating a change in the image forming characteristic of the projection optical system based on information from the incident light intensity input means. Control means (30) for controlling the imaging characteristic correcting means based on the result of the imaging characteristic calculating means.

[0009]

In order to achieve the above object, for example, the intensity of illumination light passing through the mask on the substrate stage side is sequentially stored in synchronization with the movement of the mask stage. In other words, since the illumination light intensity is stored according to the scan position of the mask, even if the energy incident on the projection optical system changes by scanning the mask during the exposure operation, the change in the imaging characteristics caused by the exposure light absorption changes. Since the illumination light intensity corresponding to the position of the mask can be used for the calculation of the above, no inconvenience occurs. Further, since the energy incident on the projection optical system is calculated in consideration of the information on the light reflected from the photosensitive substrate, a change in the imaging characteristic due to the exposure light absorption can be accurately obtained.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a projection exposure apparatus suitable for one embodiment of the present invention. Illumination light I emitted from light source 1
L passes through the shutter 2 and is adjusted to a predetermined light beam diameter by a lens system 4 including a collimator lens and the like, and then enters a fly-eye lens 6 via a mirror 5. Illumination light I
L is, for example, an excimer laser beam of KrF or ArF, a harmonic of a copper vapor laser or a YAG laser, or an ultraviolet bright line of an ultra-high pressure mercury lamp. The shutter 2 can be inserted into and removed from the optical path by a shutter driving unit 3 and controls the opening and closing of the optical path. is there.

Light rays emitted from the fly-eye lens 6 are incident on a reticle (mask) R on which a semiconductor circuit pattern or the like is drawn via relay lenses 7a and 7b, a reticle blind 8, a mirror 9, and a condenser lens 10. The combined system of the fly-eye lens 6, the relay lenses 7a and 7b, the mirror 9, and the condenser lens 10 illuminates the illumination light I emitted from each lens element of the fly-eye lens 6.
L is superimposed on the reticle R to illuminate the reticle R with uniform light intensity. The light-shielding surface of the reticle blind 8 has a conjugate relationship with the pattern area of the reticle R, and a plurality of movable light-shielding portions (for example, two L-shaped movable light-shielding portions) constituting the reticle blind 8 are connected to the motor 1.
The size (slit width, etc.) of the opening is adjusted by opening and closing by step 1. The illumination area IA for illuminating the reticle R is arbitrarily set by adjusting the size of the opening. The reticle R is vacuum-sucked on a reticle stage RST provided on the base 12, and the reticle stage RST is moved in a plane perpendicular to the optical axis IX of the illumination system.
Can be finely moved in a two-dimensional direction on the base 12 via an air bearing or the like in order to determine the position. The reticle stage RST can be moved on the base 12 in a predetermined direction (scan direction) by a reticle driving unit 13 constituted by a linear motor or the like. Reticle stage R
ST indicates that the entire surface of the reticle R has at least the optical axis IX of the illumination system.
Have a travel stroke sufficient to cross the A movable mirror 15 for reflecting the laser beam from the interferometer 14 is fixed to an end of the reticle stage RST, and the position of the reticle stage RST in the scanning direction is constantly set by the interferometer 14 at a resolution of, for example, about 0.01 μm. Is detected. Reticle stage R from interferometer 14
The position information of the ST is sent to the reticle stage control system 16, and the reticle stage control system 16
The reticle driving unit 13 is controlled based on the position information of ST, and the reticle stage RST is moved. The reticle stage RS is positioned so that the reticle R is accurately positioned at a predetermined reference position by a reticle alignment system (not shown).
Since the initial position of T is determined, the position of the reticle R is measured with sufficiently high accuracy only by measuring the position of the movable mirror 15 with the interferometer 14.

Now, the illumination light IL that has passed through the reticle R
Is incident on, for example, a projection optical system PL that is telecentric on both sides. The projection optical system PL applies a resist (photosensitive agent) on the surface of a projected image obtained by reducing the circuit pattern of the reticle R to, for example, 1/5 or 1/4. Formed on the wafer W. In the exposure apparatus according to the present embodiment, as shown in FIG. 2, the reticle R is illuminated in a rectangular (slit-shaped) illumination area IA having a longitudinal direction perpendicular to the reticle-side scanning direction (+ x direction). The reticle R is scanned at the speed indicated by the arrow Vr during exposure. The illumination area IA (the center is substantially coincident with the optical axis IX) is the projection optical system PL.
Is projected onto the wafer W through the projection area IA to form a projection area IA ′. Since the wafer W is in an inverted imaging relationship with the reticle R, the wafer W is scanned in a direction opposite to the direction of the arrow Vr (−x direction) at a speed of the size of the arrow Vw in synchronization with the reticle R,
The entire surface of the shot area SA of the wafer can be exposed. The scanning speed ratio Vw / Vr accurately corresponds to the reduction magnification of the projection optical system PL, and the pattern of the pattern area PA of the reticle R is the shot area S on the wafer W.
A is accurately reduced and transferred onto A. The longitudinal direction of the illumination area IA is formed so as to be larger than the pattern area PA on the reticle R and smaller than the maximum width of the light shielding area ST. By scanning, the entire area of the pattern area PA can be illuminated.

Returning to the description of FIG. 1, the wafer W is vacuum-sucked on the wafer holder 17 and is held on the wafer stage WST via the wafer holder 17. The wafer holder 17 can be tilted in an arbitrary direction with respect to the best image forming plane of the projection optical system PL by a driving unit (not shown), and the optical axis IX
Fine movement is possible in the direction (Z direction). The wafer stage WST is configured to be movable not only in the above-described scan direction (X direction) but also in a direction (Y direction) perpendicular to the scan direction so as to be able to move arbitrarily to a plurality of shot areas. Then, a step-and-scan operation is performed in which the operation of scanning and exposing each shot area on the wafer W and the operation of moving to the next shot exposure start position are repeated. The wafer stage driving unit 18 such as a motor moves the wafer stage WST in the XY directions. Wafer stage WS
A movable mirror 20 that reflects the laser beam from the interferometer 19 is fixed to an end of T, and the position of the wafer stage WST in the XY directions is set to, for example, 0.01 by the interferometer 19.
It is always detected with a resolution of about μm. Wafer stage W
The ST position information (or speed information) is sent to the wafer stage control unit 21, and the wafer stage control unit 21 controls the wafer stage driving unit 18 based on the position information (or speed information). Although not described in detail, the wafer W that has been previously exposed and processed by the wafer alignment system (not shown) is positioned so that the projected image of the reticle is accurately overlapped and exposed. In addition, the apparatus shown in FIG. 1 supplies an image forming light beam for forming a pinhole or a slit image toward the best image forming plane of the projection optical system PL from an oblique direction with respect to the optical axis IX direction. An oblique incidence type wafer position detection system (focus detection system) including an irradiation optical system 22 and a light receiving optical system 23 that receives, via a slit, a light beam reflected by the surface of the wafer W of the image forming light beam.
Are fixed to a support (column) 24 that supports the projection optical system PL. The configuration and the like of the wafer position detection system are disclosed in, for example, Japanese Patent Application Laid-Open No. S60-168112. The optical system PL is used to drive the wafer holder 17 in the Z direction so as to keep a predetermined interval. The wafer position information from the wafer position detection system is input to the focus position control unit 25, and the wafer position information is sent to the wafer stage control unit 21 via the main control system 100. The wafer stage controller 21 drives the wafer holder 17 in the Z direction based on the wafer position information.

In this embodiment, the angle of a parallel plate glass (not shown) provided beforehand in the light receiving optical system 22 is adjusted so that the image plane becomes the zero point reference, and the wafer position is detected. System calibration shall be performed. Further, for example, Japanese Patent Application Laid-Open No. 58-113706
A horizontal position detection system as disclosed in Japanese Patent Application Laid-Open Publication No. H10-207, or a wafer position detection system is configured to detect a focus position at any of a plurality of positions in the image field of the projection optical system PL (for example, By forming a plurality of slit images in the image field), the inclination of a predetermined region on the wafer W with respect to the image plane may be detected.

On the wafer stage WST, an irradiation amount sensor 41 is provided at a height substantially equal to the height of the surface of the wafer W. The irradiation amount sensor 41 has a light receiving surface at least equal to or larger than the projection area IA ′, and is moved to a position immediately below the optical axis IX of the projection optical system PL during measurement, so that the reticle R
And outputs a signal Sc corresponding to the intensity of the entire illumination light passing therethrough. This is used for initial setting at the time of correcting an imaging characteristic that fluctuates with the incidence of illumination light, as described in detail later.

Here, a detailed arrangement example of the interferometer 19 will be described with reference to FIG. FIG. 3 shows the wafer stage WS
It is a detailed view around T. The interferometer 19 of this embodiment includes an X interferometer (interferometer 19x ₁ , interferometer 19x ₂ ) and a Y interferometer (interferometer 19y ₁ , interferometer 19y) for measuring a position in the X direction.
₂ ) and an interferometer 19ya for alignment having an optical axis in the Y direction passing through the center OAc of the observation area OA of the off-axis alignment system (not shown). The interferometers 19x ₁ and 19x ₂ are arranged symmetrically with respect to a straight line Cx that passes through the center Ce of the projection field if of the projection optical system PL and is parallel to the X axis. The moving mirror 20x is an interferometer 19
This is a movable mirror for detecting the position in the X direction that reflects the laser light from x ₁ and 19x ₂ . The interferometers 19y ₁ and 19y ₂ are arranged symmetrically with respect to a straight line Cy passing through the center Ce of the projection field if of the projection optical system PL and parallel to the Y axis. Moving mirror 2
Reference numeral 0y denotes a moving mirror for detecting the position in the X direction that reflects the laser beams from the interferometers 19y ₁ and 19y ₂ . The wafer stage controller 21 includes a position calculator 21Xe for calculating a position in the X direction, and a yawing calculator 21Xθ, Y for obtaining a yawing amount from the Y axis of the movable mirror 20x (stage WST).
Position calculating unit 21Ye for calculating the position in the direction, movable mirror 20
A yawing calculation unit 21Yθ for calculating the yawing amount of the y (stage WST) from the X axis and a position calculation unit 21Ya for calculating a position in the Y direction at the center OAc of the off-axis alignment system are provided. Position calculation unit 21
Xe calculates the position measurements Xe in the X direction of the wafer stage WST from the average of the measurement values of interferometers 19x ₂ and the measurement value of the interferometer 19x _1. Yawing calculator 21Xθ calculates the yawing amount Xθ in moving in the X direction of the wafer stage WST from the measurement value of the measurement values and the interferometer 19x ₂ interferometers 19x _1. The position calculator 21Ye is the interferometer 1
Calculates the position measurements Ye in the Y direction of the wafer stage WST from the average of the measurement values of 9y ₁ and the measured value of the interferometer 19y _2. Yawing calculator 21Yθ calculates the yawing amount Yθ in movement in the Y direction of the wafer stage WST from the difference between the measured values of the interferometer 19y ₂ and the measurement value of the interferometer 19y _1.

The position calculating section 21Ya measures the position Ya of the wafer stage WST in the Y direction when detecting a mark on the wafer W in the off-axis alignment system. Position measurement system for alignment (interferometer 19
ya, the position detection unit 21Ya) is provided because Abbe error at the time of mark detection caused by the distance between the observation center OAc of the off-axis alignment system and the center Ce of the projection visual field if of the projection optical system PL in the x direction. This is to prevent The wafer stage WST is provided with a reference plate FM on which reference marks are formed.
Is used to measure the distance (base line) between the observation center OAc of the off-axis alignment system and the center Ce of the projection field if of the projection optical system PL. The surface of the reference plate FM has a reflective surface R ₃ of substantially zero reflectivity and reflective surface R ₂ having a reflectivity r _2, reflective surface R ₁ surface of the radiation amount sensor 41 having a reflectivity r ₁ have. Each reflecting surface calculates an offset component as described later,
Used as a reference reflecting surface for calculating the reflectivity of the wafer.

By the way, as shown in FIG.
The yawing amount of ST is measured independently using both the x-axis movable mirror 20x and the y-axis movable mirror 20y,
This is because the averaging circuit 21k averages the values of the yawing amounts Xθ and Yθ measured in both of them. In this way, since the variation in the interferometer 19x _1, 19x interferometer for ₂ and Y axis 19y _1, 19y measurements by air fluctuations in the laser beam path of the _second X-axis are averaged, and more A highly reliable yawing amount can be measured.

In the case of a stage WST for wafer exposure as shown in FIG. 3, there is not much problem. However, in the case of a stage for exposing a glass plate for manufacturing a liquid crystal display element, the movement stroke of the stage is such that a projected image on the glass plate is moved. Depending on the arrangement (pattern arrangement), it may become extremely large in one of the x direction and the y direction. In this case, on the side where the moving stroke is extremely large, one laser light path of the pair of interferometers for yawing measurement may protrude from the moving mirror near the end point of the stroke. Therefore, whether the laser beam path protrudes from the movable mirror on the X-axis side or the Y-axis side based on the pattern arrangement on the glass plate (which is known in advance by design before exposure) is examined, and the interferometer of the axis that does not protrude May be switched so as to use the yawing amount measured in step (1). Of course, when the laser beam does not protrude from the laser beam paths of the interferometers on both axes, it is needless to say that it is desirable to use the average yawing amount from the averaging circuit 21k.

In the optical path between the fly-eye lens 6 and the reticle R in the apparatus shown in FIG. 1, a part of the illumination light IL (for example, 5% light) is reflected and the remaining light is transmitted. A beam splitter 26 is provided to guide reflected light from the reticle R to a reflected light sensor 27. The reflected light sensor 27 uses a photoelectric sensor such as a silicon photodiode or a photomultiplier, receives reflected light from the wafer W via the reticle R, and outputs a signal Sb to the main control system 100. The reflected light sensor 27 is in the illumination area I
Since it is desirable to receive the entire reflected light within A (IA ′), the light may be condensed by a lens or the like or provided on a Fourier transform plane with respect to the wafer W, that is, a position conjugate with the pupil position of the projection lens PL. desirable.

The beam splitter 26 guides a part of the illumination light from the light source 1 to a photoelectric sensor 28 for detecting the light intensity of the light beam from the light source 1. The photoelectric sensor 28 receives a part of the illumination light IL reflected by the beam splitter 26 and outputs an output signal Sa to the main control system 100.
The functions of the reflected light sensor 27 and the photoelectric sensor 28 will be described later in detail.

The apparatus is provided with input means 101 such as a keyboard and a bar code reader. The input means 101 includes information on a thermal time constant of a projection optical system, information on transmittance of a reticle R, a value of an illumination slit width, Various information such as a target exposure amount and a scan speed can be input. The exit end face of the fly-eye lens 6 on which a plurality of secondary light source images are formed has a Fourier transform relationship with the pattern area of the reticle R, and a stop 29 for changing the shape of the secondary light source is provided near the exit end face. It is provided so as to be exchangeable. The diaphragm 29 restricts the shape of the secondary light source image to a ring shape, the diaphragm restricts the shape of the secondary light source image to a plurality of discrete areas decentered from the optical axis IX, and the diaphragm 29 for the secondary light source image. A circular diaphragm or the like whose size is variable without changing its center. For the ring-shaped diaphragm, see
Japanese Patent Application Laid-open No. Hei 9-16662 discloses a stop that restricts the shape of a secondary light source image, for example, a stop in which four apertures are arranged point-symmetrically with respect to the optical axis IX.
This is as disclosed in detail in JP-A-225514 and the like.

The apparatus shown in FIG. 1 has a projection optical system PL.
A correction mechanism capable of correcting the imaging characteristics is provided. Hereinafter, the correction mechanism for the imaging characteristics will be described. As shown in FIG. 1, in the present embodiment, the reticle R or the lens elements 34 and 35 are independently driven by the imaging characteristic control unit 30 to form the optical characteristics of the projection optical system PL itself and the imaging of the projected image. The characteristics can be corrected. The reticle stage RST can be finely moved by the driving element 31 in the optical axis IX direction (vertical direction). Drive element 3
Reference numeral 1 denotes a piezo, an electrostrictive element, an air damper or the like, and 3 to 4 for driving the entire reticle stage RST.
Used.

The terms of the imaging characteristics of the projection optical system PL include a focus position (image plane position), a projection magnification, distortion, field curvature, astigmatism, and the like. These values are individually corrected. It is possible. However, in this embodiment, in order to simplify the description, an example of a method of driving the lens element of the projection optical system PL particularly in the case of correcting the focal position, the projection magnification, and the field curvature in the projection optical system which is telecentric on both sides. This will be explained.

The first group of lens elements 34 closest to the reticle is fixed to a support member 36, and the second group of lens elements 35 is fixed to a support member 37. The lens element below the lens element 38 is fixed to the lens barrel 39 of the projection optical system PL. In the present embodiment, the optical axis IX of the projection optical system PL is the lens barrel 39.
Indicates the optical axis of the lens element fixed to the lens element.

A plurality of support members 36 (for example, 3
(Two are shown in FIG. 1). The driving element 32 is connected to the supporting member 37 by a driving element 32.
Here, when each of the lens elements 34 and 35 is moved in parallel in the optical axis direction, the projection magnification (the amount of enlargement or reduction of the size of the projected image) M and the field curvature C are obtained at a change rate corresponding to the amount of movement.
And the focal position F changes by a small amount. Assuming that the driving amount of the lens element 34 is z ₁ and the driving amount of the lens element 35 is z ₂ , each of the projection magnification M, the field curvature C, and the amounts of change ΔM, ΔC, and ΔF of the focal position F are expressed by the following equations. Is done.

ΔM = C _M1 × z ₁ + C _M2 × z ₂ (1) ΔC = C _C1 × z ₁ + C _C2 × z ₂ (2) ΔF = C _F1 × z ₁ + C _F2 × z ₂ (3) _Here , C _M1 , C _M2 , C _C1 , C _C2 , C _F1 , and C _F2 are constants representing the rate of change of each change amount with respect to the drive amount of the lens element.

As described above, the wafer position detection systems 22 and 23 detect the amount of deviation of the wafer surface from the optimum focus position using the optimum focus position of the projection optical system PL as a zero point reference. Therefore, the wafer position detection systems 22, 2
Electrically or optically appropriate offset amount z _{3 with} respect to ₃
Is given, by using the wafer position detection systems 22 and 23 to position the wafer surface, it is possible to correct the focal position shift accompanying the driving of the lens elements 34 and 35. At this time, the above equation (3) is expressed as the following equation.

ΔF = C _F1 × z ₁ + C _F2 × z ₂ + z ₃ (4) From the above, the driving amounts z _{1 to} z ₃ are set in the expressions (1), (2) and (4). The amount of change Δ
M, ΔC, and ΔF can be arbitrarily corrected. In addition,
Here, the case where the three types of imaging characteristics are simultaneously corrected has been described. However, if the amount of change in the imaging characteristics due to the absorption of illumination light among the optical characteristics of the projection optical system is negligible, the reason is as follows. It is not necessary to perform the above-described correction, and when the imaging characteristics other than the three types described in the present embodiment change significantly, it is necessary to correct the imaging characteristics. Further, in this embodiment, since the amount of change in the field curvature is corrected to zero or less than an allowable value, correction of astigmatism is not particularly performed.

In this embodiment, the change amount ΔF of the focal position
For (Equation (4)), for example, the wafer position detection system 2
The change amount ΔF is electrically or optically (plane-parallel) offset applied to the wafers 2 and 23, and the wafer W is moved in the Z direction using the wafer position detection systems 22 and 23, so that the projection optical system can be used. It is assumed that the surface of the wafer W is set on the best imaging plane (best focus position) of the system PL.

Here, in the present embodiment, the imaging characteristic control unit 30
Reticle R and lens elements 34 and 35
Is movable in the direction of the optical axis. In particular, the lens elements 34 and 35 are more easily controlled with greater influence on characteristics such as magnification, distortion, and field curvature (astigmatism) than other lens elements. Has become. Also,
In this embodiment, two groups of movable lens elements are used. However, three or more groups can be used. In this case, the range of movement of the lens elements can be increased while suppressing fluctuations of other aberrations. It is possible to deal with distortion (trapezoidal and rhombic distortion) and field curvature (astigmatism). Also, distortion or the like can be corrected by Z driving of the reticle R.

Further, feedback control is performed to a predetermined control target position by using together with a position sensor for monitoring the driving amount, for example, an encoder, a capacitive sensor, a light reflection type sensor, or the like. Also, even if dynamic correction is not performed during the exposure operation (during operation), if it is used only for maintenance work, it can be replaced with a fine feed mechanism with a micrometer head or a semi-fixed mechanism with a washer. is there.

As described above, the reticle R
Although an example of correcting by moving the element has been described, a suitable correction mechanism in the present embodiment may be any other method, for example, sealing a space between two lens elements or a parallel plate glass, A method of adjusting the pressure in the sealed space may be adopted. The apparatus of FIG. 1 is provided with a pressure control system 40 for adjusting the pressure in the sealed space sandwiched between the lens elements and correcting the optical characteristics (particularly magnification) of the projection optical system PL itself by a small amount. The pressure control system 40 is also controlled by the imaging characteristic control unit 30 so as to give a desired imaging characteristic to the projected image. The detailed configuration of the pressure control system 40 is disclosed in Japanese Patent Application Laid-Open No. Sho 60-78416, and the description thereof is omitted here.

As described above, by adopting the correction mechanism configured to drive the lens element or adjust the pressure in the sealed space between the end elements, the fluctuation of the imaging characteristics of the projection optical system PL due to the absorption of the exposure light. Can be adequately addressed. Next, a method of calculating the amount of change in the imaging characteristic due to absorption of exposure light will be described. Based on the amount of change in the calculated imaging characteristic, the above-described image forming characteristic correction mechanism is optimally driven. . Strictly speaking, the calculation of the amount of change
It is necessary to individually calculate each of the above-described imaging characteristics. This is because the degree of influence on each imaging characteristic is slightly different depending on the lens element constituting the projection optical system PL, and therefore, even if illumination light having the same energy is incident on the projection optical system PL, the fluctuation characteristics are different. . However, the basic calculation method is exactly the same, and the coefficients are slightly different. For the sake of simplicity, the following description will be made using the change ΔM of the projection magnification as an example.

First, the principle will be described. The change ΔM in the projection magnification occurs because the lens element inside the projection optical system PL slightly absorbs the illumination light and the temperature rises, so that the refractive index or the curvature of the lens element slightly changes. Focusing on one lens element, the lens element has energy input by illumination light, that is, absorption of heat quantity and emission of heat quantity escaping to the external lens barrel 39 and the like. Is determined. Assuming that the temperature rise and the magnification change ΔM are in a proportional relationship, it is considered that the magnification change ΔM is determined by the balance between the two. In general, when the temperature rise of the lens element is low, the absorption of heat exceeds the release and the temperature gradually rises. When they are balanced, they are in equilibrium with the saturation level. When the exposure operation that has been performed up to that time is stopped, the amount of heat is gradually released, and the temperature of the lens element decreases. However, when the temperature difference from the ambient temperature decreases, the speed of heat release slows down. This characteristic is generally called first-order lag, and can be expressed by a first-order differential equation. This is shown in FIG. FIG.
4A shows incident energy, and FIG. 4B shows magnification change characteristics when illumination light having a constant energy amount is irradiated on the projection optical system PL for a predetermined time. The change characteristic shown in FIG. 4B is a change amount ΔM ₁ (saturation level) of the final projection magnification with respect to the irradiation energy E ₁ , and the change rate ΔM
It can be determined in two values of time constant T representing ₁ / E ₁ and the temporal change. In FIG. 4, the time constant T is the final variation Δ
It can be defined as the time that varies by ^{_{ΔM 1 × (1-e -1}} ) with respect to M _1. Here, if the change rate ΔM ₁ / E ₁ and the time constant T are obtained, it is possible to calculate the magnification change amount ΔM from the estimated value of the energy E incident on the projection optical system PL based on the output Sa of the photoelectric sensor 28. More specifically, the incident energy E is constantly monitored, and the incident energy E is obtained by sequentially calculating ΔM in the main control system 100 based on the change rate ΔM ₁ / E ₁ and the time constant T. The change rate ΔM ₁ / E ₁ and the time constant T can be obtained by experimentally irradiating the projection optical system PL with illumination light and confirming the characteristics as shown in FIG. 4B. However, since a plurality of lens elements actually exist in the projection optical system PL, the overall magnification variation characteristic is expressed in the form of the sum of some first-order lag characteristics. Change rate ΔM
₁ / E ₁ and the time constant T are input to the main control system 100 by the input means 101 in advance. As described above, the change rate ΔM ₁ / E
₁ and the time constant T are coefficients of a first-order differential equation, and this differential equation is usually solved sequentially by numerical analysis such as digital calculation. If the calculation synchronization at this time is set to a predetermined time which is sufficiently shorter than the time constant T, and the value of the energy E incident on the projection optical system PL is calculated every moment according to the calculation synchronization (calculation), the main control system With 100, the change amount ΔM at that time can be calculated.

Next, a description will be given of a method of obtaining different incident energies E in accordance with the position of the reticle and obtaining fluctuation characteristics of the imaging characteristics when the amount of energy is different during one-shot exposure. Hereinafter, a method for obtaining the energy E which is incident on the projection optical system PL moment by moment will be described. When considering the incident energy on the projection optical system PL, it is necessary to consider not only the amount of light incident through the reticle but also the amount of light reflected by the wafer and incident again on the projection optical system. In the case of the scan type, the reticle R is placed in the slit-shaped illumination area I.
A for scanning, the illumination area IA
The total area of the light shielding portion of the reticle R appearing in the reticle R is
And the incident energy E to the projection optical system PL changes according to the reticle scan position. Therefore, for example, during scanning exposure, the amount of light incident on the projection optical system PL via the reticle and the amount of light reflected on the wafer and incident on the projection optical system PL again at every sampling time of the time interval Δt of several msec, for example. And the incident energy E may be calculated.

At this time, the projection optical system PL is connected via a reticle.
Is obtained based on the output Sa of the photoelectric sensor 28, and the amount of light reflected by the wafer and incident again is obtained based on the output Sb of the reflected light sensor. However, the output Sb of the reflected light sensor 27 includes the light amount information of the reflected light reflected by the reticle R and the optical member in the illumination optical system. Therefore, in this embodiment, reference reflection data for obtaining the reflection intensity of the wafer is obtained according to the scanning position of the reticle by using reference reflection plates having different known reflectances from each other. The reflectivity (reflection intensity) of the wafer was determined according to the reticle scan position. The transmittance of the reticle (the amount of transmitted light) is also determined according to the scan position of the reticle, and the energy E is determined based on such information.

Therefore, a method of calculating the incident energy E using the wafer reflectance determined based on the reference reflection data and the reticle transmittance will be described below. Assuming that the amount of light incident on the projection optical system PL via the reticle R is P and the reflectance of the wafer W is r, the total amount of incident light on the projection optical system PL is reflected by the wafer W and enters the projection optical system PL. Reflected light amount P
-It can be expressed as in equation (5) including r.

E = P × (1 + r) (5) The amount of light P can be obtained by setting the transmittance of the reticle R at the irradiated position to η, the illuminance of the light source per unit area to Ip, and the irradiated area to S. Then, it can be expressed by the following equation. P = Ip × S × η (6) Here, for the sake of convenience, the illuminance Ip is the illuminance per unit area on the wafer W surface (illuminance without a reticle), and S is the wafer W
Of the irradiation area IA ′, the point is that the relationship between ΔM and E may be finally determined, so that the light amount P may be defined on the reticle R or may be defined elsewhere. No problem.

When performing a scan type exposure, the amount of light incident on the projection optical system PL via the reticle differs depending on the position of the reticle R. Therefore, the reticle transmittance η needs to be obtained for each scan position of the reticle R. Hereinafter, a method for obtaining the reticle transmittance will be described. After moving wafer stage WST so that irradiation amount sensor 41 is positioned within irradiation region IA ', wafer stage WST
With the reticle R mounted, only the reticle stage RST is scanned, and the magnitude of the output Sc ₁ of the irradiation amount sensor 41 at that time is determined by the reticle stage RS.
The position of the reticle interferometer 14 for measuring the position of T is sequentially read in correspondence with the position coordinates (x _R ), and at the same time, the magnitude of the output Sa of the photoelectric sensor 28 is also read. And the ratio S
c ₁ / Sa is calculated and stored in a memory in the main control system 100 corresponding to the coordinate position. The storage timing (digital sampling) in the memory is, for example, the reticle interferometer 1
The resolution may be set to be constant (for example, every 0.01 μm to 10 μm) based on a resolution of 4 (for example, 0.01 μm). Since the main control system 100 is usually constituted by a digital computer, the main control system 100 is sequentially calculated with the resolution of the interferometer 14 at each position interval (or time interval) where an error in the calculation accuracy of the magnification variation does not matter. Some of the digital values of the ratio Sc ₁ / Sa may be averaged and stored, or the resolution of the interferometer 14 (or a constant moving amount coarser than that).
In a ratio Sc ₁ / Sa that sequentially calculated may be directly go to storage.

The position at which movement of the reticle stage RST to read the output Sc ₁ is stored in the main control system 100 as a reference position for reading. The output Sc ₂ of the irradiation amount sensor 41, the reticle transmittance data η (x _R ), the output Sb of the reflected light sensor 27, the reference reflectance data rx (x _R ), and the data of the offset component, which will be described later, are stored in the memory. All measurements are made based on this position.

Next, reticle R is moved to reticle stage RST.
Before mounting on the camera, a ratio Sc ₂ / Sa ′ (a constant value independent of the scanning position) between the output Sc ₂ of the irradiation amount sensor 41 and the output Sa ′ of the photoelectric sensor 28 detected at the same timing is determined in advance. Using the value of the ratio Sc ₂ / Sa ′ as the denominator,
Data sequence (waveform) of ratio Sc ₁ / Sa stored in memory
Is standardized (divided). Thus, the ratio Sc ₁ · Sa ′ of the output of the irradiation amount sensor 41 depending on the presence or absence of the reticle R
The data sequence of / Sc ₂ · Sa is obtained, and the data sequence of this ratio is stored in the memory at the same interval as the digital sampling interval of the output Sc ₁ . This output ratio Sc ₁ · Sa ′ /
Sc ₂ · Sa is the true reticle transmittance η corrected for the detection error due to the fluctuation of the illuminance Ip, and the transmittance η is the position x _R
Η (x _R ), and can be represented by a curve as shown in FIG. 5 as an example. The horizontal axis in FIG. 5 indicates the position x _R of the X direction of the reticle (scanning direction) and the vertical axis represents the reticle transmittance eta. Since the position x _R changes with time t during the scan, if the scan is performed at a constant speed,
η (x _R ) = η (t). Since the illuminance Ip is an element that varies with time, at the time of actual scan exposure, the above equation (6) is used as the equation (7), and the illuminance IP during the scan exposure is sequentially obtained from the output Sa of the photoelectric sensor 28 to obtain the equation (7). 7).

P (t) = S × η (t) × Ip (t) (7) η (t) = η (x _R ) When the illuminance Ip does not change with time, for example, a mercury discharge lamp or the like is used as a light source. Then, since the fluctuation of the illuminance Ip during the exposure of the one-shot area on the wafer W can be almost ignored, the illuminance Ip is detected and stored by the output Sa of the photoelectric sensor 28 immediately before the start of the scanning exposure, and is stored in the equation (7). Ip during calculation
(T) can be treated as a constant. At this time, the shutter ON / OFF signal indicates that when the shutter is ON, Ip
Can be treated as a constant value, and when the shutter is off, it can be treated as Ip = 0. Further, since the output of the irradiation amount sensor 41 directly represents P (t), P (t) measured before exposure is used even if η (t) is not registered in advance for each reticle. You can also. In any case, since the time t in the equation (7) uniquely corresponds to the scan position of the reticle (or wafer), the reticle interferometer 1
The transmittance data η (x _R ) is read from the memory in accordance with the measurement position x _R of No. 4, and the incident light amount P (t) is obtained in real time.

Further, since the irradiation amount sensor 41 may have a smaller light receiving area as compared with the simultaneous exposure type in which the entire surface of the reticle is illuminated at once, an inexpensive and uniform sensor having almost no illuminance unevenness in the light receiving surface ( Silicon photodiode) can be used. Further, when the light source 1 is a pulse light source, the irradiation amount sensor 41 receives the pulse light. In this case, the intensity is measured for each pulse triggered in accordance with the scanning position of the reticle R, and the output is measured. Sc may be sequentially taken in as illuminance Ip,
For example, the intensity of the pulsed light (single or multiple pulses) triggered during several to several tens of mSec may be integrated and sequentially taken as the average illuminance Ip within that time.

Next, a method for determining the reflectance r in the equation (5) will be described. As described above, not only the reflected light from the wafer W surface but also the reflected light from the reticle R surface or each lens element of the projection optical system PL enters the reflected light sensor 27. Therefore, an actual wafer reflectance is calculated by calculation in accordance with reference reflection data created using a reference reflection surface on wafer stage WST in advance. Here, the surface of the irradiation amount sensor 41 is set to a reflecting surface R having a known reflectance r _1.
1, and the surface of the reference plate FM is a reflection surface R ₂ having a known reflectance r ₂ . The reflectances r ₁ , r ₂ (r ₁ > 0, r ₂ > 0) of the _two reference reflecting surfaces with respect to the illumination light for exposure are known values measured in advance, and the two reflectances r ₁ , r Desirably, ₂ is very different. In first state where the reticle R is set, after the reflecting surface R ₁ in the projected exposure area IA 'moves the wafer stage WST to be positioned, a predetermined reticle stage RST while stopping the wafer stage WST By moving at a speed, the magnitude of the output I ₁ of the reflected light sensor 27 is digitally sampled for each scanning position of the reticle R, and sequentially stored in the memory of the main control system 100 in association with the scanning position. The timing of digital sampling and storage in the memory may be performed, for example, every fixed movement amount with reference to the resolution (eg, 0.01 μm) of the reticle interferometer 14. Also in this case, the digital sampling interval does not need to coincide with the resolution of the interferometer 14, and may be coarse, for example, every 0.2 μm to 10 μm.

Next, after moving wafer stage WST so that reflection surface R ₂ having reflectance r ₂ is located within irradiation area IA ′, reticle stage RST is moved at a predetermined speed while wafer stage WST is stopped. Then, the magnitude of the output I ₂ of the reflected light sensor 27 is sequentially stored (digitally sampled) in the memory of the main control system 100 according to the position of the reticle R. In this case the timing of storage in the memory is the same as the interval of the digital sampling of the output I _1,
Address on the memory is also a sampling position of the output I ₁ and the sampling position of the output I ₂ is set to to correspond uniquely related.

In particular, when the light source 1 is a pulse light source, the values of the outputs I ₁ and I ₂ are normalized (I ₁ / Sa) to correct the intensity variation for each pulse by using the output Sa of the photoelectric sensor 28. , I ₂ / Sa). This can be similarly applied to the case where the bright line of the mercury discharge lamp is used as the illumination light, and the standardized values I ₁ / Sa and I ₂ / Sa are stored in the memory.

FIG. 6 shows the relationship between the output of the reflected light from the reference reflecting surface and the reflectance. FIG. 6 shows a reticle R 1
Values I ₁ ,
The vertical axis represents I ₂ (or I ₁ / Sa, I ₂ / Sa), and the horizontal axis represents the reflectance. As shown in FIG.
_{When a} straight line passing through ( ₁ , I ₁ ) and (r ₂ , I ₂ ) is drawn, the reflectance (reflected intensity) rx of the wafer is obtained from the output value of the reflected light sensor 27 obtained at this scanning position.
That is, assuming that the output of the reflected light sensor 27 when the reticle R comes to the scanning position during the actual exposure is Ix, the wafer reflectance rx at this time becomes the reference reflection data in the memory corresponding to the scanning position. After reading I ₁ and I ₂ , rx = [(r ₂ −r ₁ ) / (I ₂ −I ₁ )] × (Ix−
I ₁ ) + r ₁ (8) Note that a method may be used in which three reference reflection surfaces having different reflectances are used, and the straight line in FIG.
Also in this case, the area of the reference reflection surface can be smaller than that of the collective type. When receiving the pulsed light, the reflected light sensor 27 may measure the intensity for each pulse, or may integrate power for a short period of time, for example, several to several tens of mSec, and output the average power. Good. In any case, before the actual exposure, the data strings of the outputs I ₁ and I ₂ stored in the memory or the formula (8) are created as the reference reflection data for each device position (sampling position) of the reticle R, and the data is stored in the memory. save. When the output I ₁ I ₂ is standardized by the output Sa, the output Ix of the reflected light sensor 27 for obtaining the actual wafer reflectance rx is also standardized by the output Sa and then substituted into the equation (8). Needless to say.

Here, the laser light reflected from the reference reflecting surface is used.
Output I of reflected light sensor 27 for each scanning position of the tickle
₁(X_R), I_Two(X_RReference reflection data created as)
Of the reticle of the reflected light from the wafer W during the actual exposure.
The output Ix (x_R) Example
As shown in FIG. The vertical axis in FIG. 7A is the intensity I of the reflected light.
x indicates the position of the reticle in the X direction._RIndicates that
Scanning of reticle R is at position x _R1To x_R2Done over
Shall be. Then, for example, the first show on the wafer W
Ix of the reflected light sensor 27 during the actual exposure of the cut area
(X_R) And the previously stored I
₁(X_R), I_Two(X_R) Data and fixed constant r₁, R
_TwoThe reflectance data according to the reticle scanning position.
Tarx (x_R) Is based on equation (9) based on equation (8) above.
Is calculated. The reflectance data rx (x_R) Is the output I
₁(X_R), I_Two(X_R) Digital sampling interval
At the same sampling interval as above and uniquely with the scanning position
It is stored in the memory at the corresponding address. Reticle position
Reflectance data rx (x_R) Is shown in FIG.
You. The vertical axis of FIG. 7B shows the wafer reflectance, and the horizontal axis shows the laser reflectance.
Scanning position x in the X direction of the tickle_RIs shown.

Rx (x _R ) = [(r ₂ −r ₁ ) / (I _{2
(X R) -I 1 (x} R)) ] × (Ix (x _R) -I
₁ (x _R )) + r ₁ (9) Since the position x _R changes with time, assuming that the reticle stage RST during actual exposure is moving at a constant speed, the reflectance data rx (x _R ) is rx (T)
The formula (7) and the formula (9) are substituted into the formula (5) to obtain a predetermined time Δ
The main control system 100 calculates an energy value E (t) for each t.

Next, the incident energy E to the projection optical system PL
And the calculation of the amount of change in the imaging characteristics of the projection optical system PL will be described with reference to FIG. Here, for the sake of simplicity, the magnification variation ΔM of the projection optical system PL will be described. FIG. 8A is a diagram showing the incident light amount E to the projection optical system PL. In the figure, Ea, Eb, and Ec indicate the energy incident on the projection optical system PL. In FIG. 8A, the instantaneous value or the average value of the incident energy at the position of the reticle stage RST within the predetermined time interval Δt (for example, several msec to several tens msec) is set as the incident energy E. In FIG. 8A, predetermined times (hereinafter referred to as “sampling times”) at predetermined time intervals Δt are denoted by t ₁ , t
₂ , t ₃ , t ₄ , and t _5, and the corresponding positions of the reticle stage RST are x ₁ , x ₂ , x ₃ , x ₄ , and x ₅ . The timing for starting the measurement of the sampling time starts when the reticle stage RST reaches the reference position at the time of storing the various data described above, and the positions x _{1 to} x ₅
Also, it is desirable to match the position of various data with the position when the data is stored in the memory as much as possible. Of course, reticle stage RST is controlled to reach a predetermined speed before reaching the reference position.

The main control system 100 operates at the sampling time t.₁so
Reticle stage RST position x ₁Transmittance η at
(X₁) And the reflectance rx (x₁) And illuminance Ip (t₁) And c
Irradiation area of wafer W (irradiation determined by reticle blind 8)
Area) IA 'and equations (5), (7), (9)
Sampling time t₁Incident on the projection optical system PL at
Energy E (t₁) = Ea is calculated as an estimated value.
As described above, when the light source is a light source such as a mercury discharge lamp,
Opening / closing information of printer 2 (1 if open, 0 if closed)
Weight) and Ip = constant value, treating Ip (t) as a constant.
I can. Note that the transmittance η (x₁), Reflectance rx
(X₁X)₁Is the sampling time t₁
Does not correspond to the sampling time t₁Subsequent
The transmittance η (x stored at the nearest position x_R), Reflectance
rx (x_R) Should be used. Also, shutter
-2 opening / closing information (1 or 0)
If shutter 2 is open, equation (5),
The calculation according to (7) and (9) is executed, and₁) = Ea
And when shutter 2 is closed, equation (5)
E (t) without performing the operations of (7) and (9)₁) = 0 and
May be used to

The following sampling time t_Two~ T_Fiveabout
Similarly, the incident energy is obtained. Here is a sump
Ring time t₁, T_ThreeThe incident energy calculated by
a, sampling time t_Two, T_FiveIncident energy calculated by
Lug is Eb, sampling time t_FourIncident calculated by
Energy is represented by Ec. In addition, sampling time
Interval Δt (for example, sampling time t₁And t_TwoBetween
Using the average value of each data at the time interval)
You may ask for lugi. Specifically, for example,
The transmittance data η (x_R), Reflectance data rx (x
_R) Is set at 25 on the reticle.
μm and sampling time t₁And t_TwoSun between
The pulling time interval Δt is 5 msec and the scanning speed V is
When 50 mm / sec, sampling time interval Δ
The distance L that the reticle stage moves during t is L = V ×
Δt = 250 μm. Transmittance data η (x_R), Anti
Emissivity data rx (x_R) Is the digital sampling interval
Since every 25 μm, the sampling time t₁And Sampling
Time t_TwoWithin the sampling time interval Δt between
Pieces of sampling data are transmittance data η (x_R) And anti
Emissivity data rx (x_R) And obtained for each. So
Here, the ten sampling data are converted into transmittance η
(X_R) And the reflectance rx (x_R) And average for each
Sampling data at sampling time t_TwoTransmittance data at
Η (x_Two) And the average reflectance rx (x_Two)
Is also good. And the sampling time t_TwoTransmittance η (x
_Two) And the reflectance rx (x_Two) And illuminance Ip (t_Two), Shut
Opening / closing information of data 2 (1 if open, 0 if closed)
Weight) and the irradiation area of the wafer W (with the reticle blind 8)
(Irradiation area to be determined) and equations (5), (7), (9)
Sampling time t based on_TwoOptical system P at
L incident energy E (t _Two) = Eb as an estimated value
calculate. At this time, the light source 1 emits the pulse light as described above.
If the light source emits light, the sampling time t₁And sun
Pulling time t_TwoWithin the sampling time interval Δt between
Power of the unit time and average it over the unit time
Power Ip (t_Two). Transmittance η (x_R)When
The reflectance rx (x _R) Digital sampling interval is sun
The reticle stage moves during the pulling time interval Δt.
Resolution smaller than the distance L
The distance L is the scanning direction of the illumination area IA.
Is determined to be smaller than the width of. One shot
Thereafter, the reflectance rx (x_R) Is calculated based on equation (9).
Reflection stored in memory during one-shot exposure
Rate data rx (x_R) To find the incident energy E
You may make it.

Next, the calculation of the amount of change in the optical characteristics of the projection optical system PL based on the amount of incident energy per unit time will be described with reference to FIG. ΔM in FIG. 8 (B)
s indicates a magnification change characteristic depending on the incident light amount E.
As shown in FIG. 8B, the magnification change characteristic with respect to the incident energy E is ΔM / E and the time constant T as shown in FIG.
Characteristics. Therefore, the magnification change amount corresponding to the incident energy at the position corresponding to each time (time at each predetermined time interval) is determined by ΔM / E and the time constant T as shown in FIG.
It is obtained from the magnification variation characteristic as described above.

A specific description will be given with reference to FIG.
The magnification change amount ΔM ₁ that changes between the sampling times t _{0 and} t ₁ according to the energy Ea is obtained from the relationship of ΔM / E. The relationship of ΔM / E is obtained in advance by experiments and the like as described above. Similarly, the magnification change amount ΔM ₂ that changes between the sampling times t _{1 and} t ₂ depending on the energy Eb is obtained from the relationship of ΔM / E. Sampling time t ₁
Attenuation factor of magnification between ~t ₂ is defined by the time constant T thermal, time according to the time constant T from the initial value between the sampling times t ₁ ~t ₂ (in this case .DELTA.M ₁₎ Together with the attenuation amount. Therefore, the magnification change amount at the sampling time t ₂ is ΔM ₁ + ΔM ₂
Is the value obtained by subtracting the amount of attenuation between sampling times t _{1 and} t ₂ from the total value of. Similarly, the magnification change amount ΔM ₃ that changes between the sampling times t _{2 and} t ₃ by the energy Ea, and the sampling time t by the energy Ec
₃ magnification variation .DELTA.M ₄ which changes during ~t _4, the magnification variation .DELTA.M ₅ which changes during the sampling time t ₄ ~t ₅ by the energy Eb is determined from the relation .DELTA.M / E.
Then, similarly, the amount of attenuation between each sampling time is obtained, and the final magnification change amount at each sampling time can be obtained. FIG. 8 (B) shows an envelope connecting the values at each sampling time as a variation characteristic of the magnification.
Can be obtained. Such a calculation method for gradually obtaining the magnification fluctuation characteristic from discrete magnification fluctuation values is disclosed in JP-A-60-78454 and JP-A-62-136821.

Next, a method of correcting the magnification will be described. The imaging characteristic control unit 30 determines the control amount of the pressure control system 40 or the drive amount of the drive elements 31, 34, and 35 so as to change the magnification according to the magnification change characteristic shown in FIG. Is corrected. However, the imaging characteristic control unit 30
Is used exclusively for adjusting the projection magnification M in the direction perpendicular to the scanning direction, and it is necessary to slightly change the relative speed of the reticle R and the wafer W during scanning with respect to the magnification in the scanning direction. Therefore, in order to change the size of the projected image isotropically over the entire surface of the shot area, the relative speed must be finely adjusted according to the magnification adjustment amount corrected by the imaging characteristic control unit 30.

The method of correcting a change in magnification has been described above, but other image forming characteristics can be similarly corrected. Note that a plurality of patterns of the reticle R are sequentially exposed on the wafer W. However, in order to improve productivity, the wafer stage WST (reticle stage RST) does not always scan in one direction, but scans every shot row on the wafer. Exposure may be performed while scanning alternately in the opposite direction. In other words, after exposing one shot row, there is a case where another shot row is exposed while scanning in the reverse direction (exposure while reciprocating). The above-described sampling of the transmittance data η, the reference reflectance data, and the like is performed by storing or calculating according to the position of the reticle R while moving the reticle in one direction (for example, the −x direction). Therefore, when the scan direction of wafer stage WST is alternately different in the opposite direction for each shot row of the wafer (when the scan direction of reticle stage RST is alternately different in the -x direction and the + x direction), transmission is performed according to the scan direction. The reading direction of the rate data η and the reflectance data is switched. That is, when scanning is performed in a direction opposite to the scanning direction of the reticle stage RST in which the transmittance η and the reference reflectance data are stored, reading of the transmittance η, the reference reflectance data, and the like from the memory is performed in the reverse direction.

Here, it is also possible to obtain the average transmittance and the average reflectance during scanning and use equations (5) and (6) as they are. This method is also a solution, but the accuracy deteriorates because the average transmittance and the average reflectance during one scan can be handled only by an averaged amount, and the reflectance can be calculated only after one scan. There is a problem that. Whether the deterioration of the accuracy by this method is within an allowable range depends on the accuracy required for calculating the magnification change ΔM,
The amount of change in magnification change ΔM during one scan, or the comparison between the time of one scan and the length of time constant T, or the difference in transmittance η of reticle R used due to the position of reticle R;
It is determined in consideration of the difference between the reflectivity r of the wafer W and the position of the reticle R. However, the time for one scan depends on the sensitivity of the resist, and the uniformity of the transmittance of the reticle used is also an uncertain factor. Therefore, in the present embodiment, the intensity of the reflected light from the wafer is determined based on the reference reflectance data created based on the intensity of the reflected light from the reference reflecting surface according to the position of the scan of the mask, and during the exposure operation. By scanning the reticle, a correct reflectance can be obtained even if the intensity of the reflected light changes according to the position of the reticle.

Next, a second embodiment of the present invention will be described. In the second embodiment, the light amount information (hereinafter, referred to as an “offset component”) reflected by the reticle R or the optical member in the illumination optical system is obtained without calculating the reference reflectance data using the reference reflection surface. The first embodiment differs from the first embodiment in that a value obtained by subtracting the offset component from the output Sb of the reflected light sensor 27 is used as the amount of light reflected by the wafer and incident again on the projection optical system PL. In the second embodiment, the same members as those in the first embodiment are denoted by the same reference numerals. Further, in this embodiment, information for obtaining the light amount (light energy) incident on the projection optical system PL via the reticle, that is, the transmittance of the reticle (in this embodiment, the light amount in the illumination area IA and the light shielding portion of the pattern) ) Is detected based on the output of the irradiation sensor 41 and the output of the light source sensor 28.

A description will now be given of obtaining the amount of light incident on the projection optical system PL via the reticle. Main control system 1
Reference numeral 00 denotes a value in the main control system 100 in which the ratio Sc / Sa of the output Sa from the light source sensor 28 to the output Sc of the irradiation amount sensor 41 is synchronized with the movement position of the reticle stage RST on which the reticle R is mounted for one scan. Store in memory. That is, the main control system 100 moves the reticle stage RST (the wafer stage WST is stationary), and outputs the output Sa from the light source sensor 28 and the irradiation amount sensor 4 according to the position of the reticle stage RST detected by the reticle interferometer 14.
The ratio Sc / Sa with respect to the output of 1 is converted into a time-series digital value and stored in a memory in the main control system 100. The data of this ratio becomes information corresponding to the change in transmittance during scanning of the reticle, and this ratio is hereinafter referred to as Rh. The storage timing (digital sampling) in the memory is determined by the resolution (for example, 0.01 μm) of the reticle interferometer 14 as described above.
With a constant moving amount (for example, 0.01 μm to 10 μm)
(every μm). The output Sa from the light source sensor 28 and the output Sc from the irradiation amount sensor 41 that can change at each position of the stored reticle stage RST.
Is stored in the memory according to the position of the reticle stage RST. At the time of actual exposure, for example, at every predetermined time of about several milliseconds, the ratio Rh stored in advance in the memory corresponding to the position of the reticle stage RST is read, and the value is output to the output value Sa of the photoelectric sensor 28 at the time of actual exposure. (The output value of the photoelectric sensor 28 every predetermined time) (S
a · Rh) is an estimated value of the amount of light (energy) incident on the projection optical system PL via the reticle every predetermined time.
Since the main control system 100 is usually composed of a digital computer, the ratio Rh or the multiplication result Sa · Rh is averaged and stored as in the digital sampling of various data in the first embodiment. Or the resolution of the interferometer 14 (or a coarser resolution)
The ratio Rh or the multiplied value Sa · Rh sequentially calculated in the above may be stored as it is.

Next, detection of information on the amount of reflected light from the wafer will be described. When considering the incident energy on the projection optical system PL, it is necessary to consider not only the amount of light incident via the reticle but also the amount of light reflected by the wafer and incident again on the projection optical system PL. Therefore, the projection optical system P
The amount of light incident again on L is determined by the output Sb of the reflected light sensor 27.
Detect based on The main control system 100 moves the reticle stage RST by one scan while the reticle R is mounted, and performs time-series photoelectric conversion from the reflected light sensor 27 in accordance with the position of the reticle stage RST detected by the reticle interferometer 14. The signal Sb (light amount information) is stored (digitally sampled) in a memory in the main control system 100. The timing of storing the data in the memory may be set, for example, every fixed movement amount with reference to the resolution (for example, 0.01 μm) of the reticle interferometer 14. Also in this case, the interval of digital sampling does not need to match the resolution of the interferometer 14, and may be coarse, for example, every 0.2 μm to 10 μm.

At this time, the output S from the reflected light sensor 27
b includes the light amount information of the light reflected by the reticle R and the optical member in the illumination optical system. Therefore, the reticle is scanned after the reference reflection surface of the reference plate FM having the reflection surface whose reflectance is almost zero is positioned in the projection area IA 'of the projection optical system PL, and the reflected light is reflected by the reflected light sensor. 27, and a change in its output Sb is detected by a reticle stage RST.
Is stored in the memory according to the position of. The stored data becomes light amount information of the light reflected by the reticle R and the optical member in the illumination optical system, and is hereinafter referred to as an offset component. At the time of actual exposure, the stored offset component may be subtracted from the output value Sb from the reflected light sensor 27.

When the photoelectric sensor 28, the irradiation amount sensor 41, and the reflected light sensor 27 receive the pulse light, the intensity may be measured for each pulse, or may be measured for a short period of time, for example, several to several tens. The power in the unit time of mSec may be integrated and output as the average power in the unit time. Next, calculation of the amount of incident light E to the projection optical system PL will be described with reference to FIG.

Method for calculating the amount of incident light E to the projection optical system PL
The calculation of the amount of change in the imaging characteristics of the projection optical system PL
It is determined in the same manner as in the example. This will be briefly described below. Book
In the embodiment, Ea, Eb, and Ec in FIG.
From the reticle side using the position of the RST stage as a variable
Light quantity incident on the projection optical system PL and projection optics from the wafer side
This is the sum with the amount of light that reenters the system PL. Main control system 100
Is the sampling time t ₁Output S of the light source sensor 28
a and the output Sb of the reflected light sensor 27 are respectively detected. main
The control system 100 sets the sampling time t₁Position x corresponding to
₁Sa from the photoelectric sensor 28 and the irradiation amount sensor
-41 ratio Rh and offset component read from memory
You. The main control system 100 outputs the output S of the photoelectric sensor 28.
a multiplied by the ratio Rh and the output of the reflected light sensor 27
Subtract the offset component at that position (or time) from Sb
Add the value that was found. The main control system 100 performs this addition.
Value and shutter 2 opening / closing information (1 if open, 1 closed
Weight if 0) and the irradiation area of the wafer W (reticle
(Irradiation area determined by line 8) IA '
Pulling time t₁Energy to the projection optical system PL at
Lugie Ea is calculated as an estimated value.

[0065] The ratio Rh and when the position x ₁ which stores the offset component does not correspond to the sampling time t _1, the ratio Rh and offset components stored in the sampling time t ₁ after the nearest position x You should use. In the same manner for the following sampling time t ₂ ~t ₅ obtains the incident energy. Here, the incident energy corresponding to the sampling times t ₁ and t ₃ is Ea, and the incident energy corresponding to the sampling times t ₂ and t ₅ is E E
b, the incident energy corresponding to the sampling time t ₄ is represented by Ec.

Incidentally, similarly to the first embodiment, the incident energy is obtained by using the average value of each data at the sampling time interval Δt (for example, the time interval between the sampling times t ₁ and t ₂ ). You may. Specifically, for example, the interval between the above-mentioned ratio Rh and the digital sampling of the offset component is set to every 25 μm on the reticle, and the sampling time interval Δt = 5 between the sampling times t ₁ and t ₂ is set.
When msec and scan speed V = 50 mm / sec, ten pieces of sampling data are obtained for each of the ratio Rh and the offset component within the sampling time interval Δt between the sampling time t ₁ and the sampling time t ₂ . Accordingly, similarly to the first embodiment, the incident energy Eb may be obtained based on data obtained by averaging ten pieces of sampling data for each of the ratio Rh and the offset component.

Once the incident energy is obtained, the amount of magnification change at the sampling time is calculated by Δ in the same manner as in the first embodiment.
From M / E, the decay rate between each sampling time is obtained from the time constant T. Then, an envelope connecting the values at each sampling time is determined as the magnification fluctuation characteristic, and the magnification fluctuation characteristic shown in FIG. 8B can be obtained. And FIG.
The imaging characteristic control unit 30 determines the control amount of the pressure control system 40 or the drive amount of the driving elements 31, 34, and 35 so as to change the magnification according to the magnification change characteristic as shown in FIG. Is corrected.

Also in this embodiment, the ratio Rh and the offset component are taken in by moving the reticle stage RST in one direction. Therefore, the reticle stage RS is moved in a direction different from the direction in which the ratio Rh and the offset component are captured.
When scanning T, the reading of the ratio Rh and the offset component is performed from the opposite direction. In the above-described first and second embodiments, the information relating to the reticle transmittance and the information relating to the reflected light of the wafer are stored in accordance with the reticle coordinates. The same effect can be obtained even if the data is stored as a reference. In the case of the wafer stage coordinate reference, it is necessary to reset the count of the interferometer to 0 every time the scan is started or to store the coordinates of the scan start point.
Further, in the case of the time reference, it is necessary to change the time axis scale because the scanning speed is different when the exposure time is different due to the resist sensitivity or the like. Note that, although the accuracy is slightly lowered in the above-described embodiment, the change characteristic of the imaging characteristic of the projection optical system PL may be obtained based only on the amount of light incident on the projection optical system PL via the reticle.

The change of the illumination condition due to the exchange of the diaphragm 29 is also described.
Furthermore, the light beam passing positions in the projection optical system PL are different.
Therefore, the change characteristics of the imaging characteristics are different. For example, regarding the magnification change
Thermal time constant, etc. Therefore, the aperture 29
Information on the changing characteristics of the imaging characteristics for each changing lighting condition
(Eg, thermal time constant) must be stored again. FIG.
Is a plan view of the reticle blind 8 in FIG.
Field if, and each arrangement relation of the pattern area PA of the reticle R.
The reticle blind 8 is shown here in two shades
It is composed of plates 8A and 8B. The light shielding plate 8B is a U-shaped flat
It has a surface shape and has an illumination area in the scan direction (x direction).
Straight edge EGx that defines the area_TwoAnd the scan direction
A straight edge E defining an illumination area with respect to the intersecting y-direction
Gy ₁, EGy_TwoAnd On the other hand, the light shielding plate 8A is
In order to define the illumination area with respect to the
B edge EGx_TwoStraight edge EGx parallel to₁With
It is movable in the x direction with respect to the light shielding plate 8B. This
Thereby, the scanning direction of the slit-shaped illumination area IA is
The width is variable. The light shielding plate 8B is also shifted in the x direction.
EGx that defines the scan direction as movable₁, EG
x_TwoMay be set symmetrically from the optical axis IX.
No. FIG. 10 shows the reticle through the reticle blind 8 of FIG.
A perspective view three-dimensionally showing the intensity distribution of the illumination light reaching the tickle R.
In the figure, the direction of the optical axis IX is defined as the intensity axis I. illumination
When using a continuous light source such as a mercury discharge lamp as the light,
It doesn't really matter, but when using a pulsed light source,
Illuminance distribution in the scan direction is a clean rectangular shape
And the amount of overlap at both ends in the scan direction of the illuminance distribution
One on wafer W due to variation in the number of superpositions
In the shot area, unevenness in the exposure amount is likely to occur.

Therefore, as shown in FIG.
At least at the end in the scanning direction,
(Width ΔXs). Figure 10
Therefore, the length YSp of the illuminance distribution in the y direction is
Determined to cover the length of the turn area PA in the y direction
And the length of the illuminance distribution in the x direction (slit width) XSp
Is the target exposure amount for the photoresist on the wafer W,
Scan speed of wafer stage RST and wafer stage WST
Degree, pulse oscillation frequency for pulsed light source, illumination light intensity
It is determined optimally in consideration of the degree. As shown in FIG.
In order to have a slope of width ΔXs at both ends of the illuminance distribution
Is the edge EGx of the light shielding plate 8A in FIG.₁And light shielding plate 8B
Edge EGx_TwoIs conjugated to the pattern surface of reticle R.
From the desired position in the direction of the optical axis IX by a certain amount,
EGx₁, EGx_TwoRetick a slight defocused image of
What is necessary is just to project on R. However, non-scanning method
Direction edge EGy₁, EGy_TwoAbout the reticle R
To form a sharp image on the pattern surface, use the edge EG
y₁, EGy_TwoIs a position conjugate to the pattern surface of reticle R
Need to be placed accurately. Therefore, the edge EGy
₁, EGy_TwoAre precisely placed in the conjugate plane, and the edge EG
x₁, EGx_TwoIs the edge EGy₁, EGy_TwoSurface position
In a plane slightly shifted to the light source side. Also pickpocket
The longitudinal dimension (length YSp) of the socket-shaped illumination area IA is
To make it variable, the edge EGy₁, EGy _TwoAlso y
Must be movable in the direction. Note that y in the illuminance distribution in FIG.
The direction becomes uniformly inclined like the imaginary line LLi
The position ya in the y direction in FIG.₁Exposed by
Part within the boat area and the position ya_TwoShot exposed at
In this case, the exposure amount is different from that in the area inside the target area. There place
Place ya₁Strength I (ya₁) And position ya_TwoStrength I
(Ya_Two) And the ratio I (ya)₁) / I (ya
_Two), The slit width XSp is finely adjusted in the y direction.
Good to do. That is, the y direction of the slit-shaped illumination light IA
Position ya₁The width in the scanning direction at XSp (y
a₁), Position ya_TwoThe width in the scanning direction at XSp (y
a_Two), I (ya₁) / I (ya_Two) = XSp
(Ya_Two) / XSp (ya₁D)
EGx₁And EGx_TwoAre relatively parallel in the xy plane
Tilt (rotate) from the state. In short, Figure 9
Slit-shaped blind opening slightly shown in trapezoidal shape
It is. In this way, the slit-shaped illumination light
Slight illumination unevenness (uniform inclination) in the non-scanning direction of
The exact exposure at each point in the shot area.
Will be obtained.

When a pulse light source is used, it is necessary to perform pulse emission in a specific positional relationship while the reticle R and the wafer W are relatively scanned. FIG. 11 schematically shows the illuminance characteristics in the scanning direction when pulse light emission is performed in the specific positional relationship. In the case of a pulsed light source, the peak intensity value varies for each pulse, and when the average value is Im, the width (X) of the slit-shaped illumination area IA defined by half the intensity Im / 2 in the scanning direction (X
Pulse emission (trigger) at each distance interval such that (Ps + ΔXs) is exactly divisible by a predetermined integer value Np (except 1).
It does. For example, when the width (XPs + ΔXs) of the slit-shaped illumination area IA on the reticle is 8 mm,
Assuming that the integer value Np is 20, the pulse light source may emit light every time the reticle R scans by 0.4 mm. The integer value Np is nothing but the number of pulses superimposed on an arbitrary point on the wafer W. For this reason, in order to average the variation of the peak intensity value for each pulse and achieve the desired exposure accuracy on the wafer, the minimum value of the integer value Np is automatically determined according to the variation of the intensity for each pulse. Come. By analogy with the current ability of a pulsed light source (such as an excimer laser), the minimum value of the integer value Np is about 20.

In FIG. 11, since Np is schematically represented as 5, the inclination of the end of the illuminance distribution of the first pulse in the scanning direction is the inclination of the tip of the illuminance distribution of the sixth pulse in the scanning direction. And overlap. At the start or end of scan exposure, pulse oscillation starts from a state where the entire slit-shaped illumination area IA (XPs + 2ΔXs in width) is located outside the pattern area PA of the reticle R, and the entire illumination area IA (width XPs + 2ΔXs)
Stops the pulse oscillation in a state in which reaches the outside of the pattern area PA.

The trigger method of the pulse light source is as follows.
One is possible. In response to a measurement value of the laser interferometer 14 (or 19) that measures the position of the reticle stage RST (or the wafer stage WST) in the scanning direction, a trigger signal is sent to the pulse light source every predetermined movement amount. Is a position synchronization trigger method for sending The other is the reticle stage RS
T, a constant time interval (for example, 2 msec) responding to the constant speed while relying on the constant speed control of the wafer stage WST.
This is a time synchronization trigger method in which a clock signal is generated every time and the clock signal is sent to a pulse light source as a trigger signal. Since both methods have advantages and disadvantages, they may be appropriately used.
However, in the time synchronization trigger method, the generation start timing and the stop timing of the clock signal are determined by the laser interferometer 1.
It must be determined in response to 4 or 19 measurements.

When giving the highest priority to shortening the exposure processing time of one shot area, the reticle is set so that the pulsed light source oscillates at the rated maximum oscillation frequency on the assumption that the target exposure amount can be obtained. It is desirable to set the speed of the stage RST, the speed of the wafer stage WST, the width (XPs) of the slit-shaped illumination area IA, and the peak intensity of the pulse.

Further, as described in each of the above embodiments, only the reticle R is scanned, and the output Sa of the photoelectric sensor 28 is output.
When sampling the output Sb of the reflected light sensor 27 to create various data, or sampling the output Sa or Sb during scan exposure when the pulsed light source is oscillating by the time synchronous trigger method, Sampling may be performed in response to a trigger clock signal.

[0076]

As described above, according to the present invention, even in the scan exposure method, the imaging characteristics can be corrected without error, and the image of the mask pattern can be formed on the substrate with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a scan type exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing scan exposure in the apparatus of FIG.

FIG. 3 is a diagram showing details around a wafer stage of the apparatus of FIG. 1;

FIG. 4 is a diagram showing a relationship between incident energy and magnification change.

FIG. 5 is a diagram illustrating the incident energy and the amount of change in the imaging characteristic when the incident energy is different for each position (time).

FIG. 6 is a diagram showing a relationship between a reflectance and a reference reflectance.

FIG. 7 is a diagram showing a change in reticle transmittance when a reticle is moved.

FIG. 8 is a diagram for explaining the output of the reflected light sensor on the reference reflecting surface and the principle of the reflectance calculation method.

FIG. 9 is a diagram illustrating a relationship between a planar shape of a reticle blind and a projection field of view.

FIG. 10 is a perspective view three-dimensionally showing an illuminance distribution of illumination light.

FIG. 11 is a diagram schematically showing an illuminance distribution in a scanning direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 13 ... Reticle stage drive part 18 ... Wafer stage drive part 22 and 23 ... Wafer position detection system 25 ... Focus detection part 27 ... Reflection light sensor 28 ... Light source sensor 30 ... Imaging characteristic control part 31, 32, 33 ... Driving element 36 Irradiation sensor 40 Pressure controller 100 Main control system R Reticle W Wafer FM Reference plane RST Reticle stage WST Wafer stage

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-181416 (JP, A) JP-A-2-74024 (JP, A) JP-A-63-58349 (JP, A) 291117 (JP, A) JP-A-5-144700 (JP, A) JP-A-2-106917 (JP, A) JP-A-2-229423 (JP, A) JP-A-4-277612 (JP, A) JP-A-4-196513 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20

Claims (42)

(57) [Claims] An illumination optical system for illuminating an illumination light from a light source to a mask provided with a predetermined pattern and illuminating the mask in a predetermined illumination area and forming a pattern image of the mask on a photosensitive substrate. A mask stage that holds the projection optical system and the mask and moves the mask in a plane perpendicular to the optical axis of the projection optical system; and an imaging characteristic correction unit that corrects the imaging characteristics of the projection optical system. In a projection exposure apparatus for exposing the entire surface of the circuit pattern by relatively moving the mask and the illumination region, a position of the mask of the illumination light incident on the projection optical system via the mask Incident light intensity input means for inputting an intensity according to the following; imaging characteristic calculating means for calculating a change in the imaging characteristic of the projection optical system based on information from the incident light intensity input means; Projection exposure apparatus characterized by, based on the result of the characteristic computing means and a control means for controlling the imaging characteristic correction unit. 2. A storage means for storing information from said incident light intensity input means in accordance with a position of said mask, and a reading means for reading out information stored in said storage means in accordance with the position of said mask. The apparatus of claim 1, wherein: 3. The apparatus according to claim 2, wherein said reading means reads information stored in said storage means according to the position of said mask at predetermined time intervals. 4. The apparatus according to claim 1, wherein said incident light intensity input means has a measuring means for measuring the light intensity transmitted through said projection optical system. 5. An illumination optical system for illuminating illumination light from a light source to a mask provided with a predetermined pattern and illuminating the mask in a predetermined illumination area, and forming a pattern image of the mask on a photosensitive substrate. A mask stage that holds the projection optical system and the mask and moves the mask in a plane perpendicular to the optical axis of the projection optical system; and an imaging characteristic correction unit that corrects the imaging characteristics of the projection optical system. In a projection exposure apparatus for exposing the entire surface of the circuit pattern by relatively moving the mask and the illumination region, a position of the mask of the illumination light incident on the projection optical system via the mask Incident light intensity input means for inputting an intensity according to the following; and a reflected light intensity for inputting an intensity corresponding to the position of the mask of the illumination light reflected by the photosensitive substrate and re-entering the projection optical system. An input unit; an imaging characteristic calculating unit that calculates a change in an imaging characteristic of the projection optical system based on information from the incident light intensity input unit and the reflected light intensity input unit; Control means for controlling the imaging characteristic correcting means based on the result. 6. An apparatus according to claim 5, wherein said reflected light intensity input means has a measuring means for measuring the intensity of light reflected by said photosensitive substrate. 7. A projection exposure apparatus that scans and exposes the substrate by moving the substrate in synchronization with the movement of the mask and projecting an image of the pattern of the mask onto the substrate. A projection optical system for projecting an image on the substrate, and, during the scanning exposure, a change in an imaging state of a projection image of the pattern projected on the substrate in accordance with energy incident on the projection optical system. A projection exposure apparatus, comprising: calculation means for calculating. 8. An image forming apparatus according to claim 1, further comprising adjusting means for adjusting an imaging state of a projected image of said pattern projected on said substrate, based on a calculation result of said calculating means during said scanning exposure. The apparatus according to claim 7, wherein: 9. A projection exposure apparatus that scans and exposes the substrate by moving the substrate in synchronization with the movement of the mask and projecting an image of the pattern of the mask onto the substrate. A projection optical system for projecting an image on the substrate, and adjusting an image forming state of a projected image of the pattern projected on the substrate according to energy incident on the projection optical system during the scanning exposure. A projection exposure apparatus, comprising: adjusting means. 10. A system according to claim 7, further comprising a sensor for measuring the energy of the illumination light passing through said projection optical system in order to determine the energy incident on said projection optical system. An apparatus according to claim 1. 11. A device according to claim 7, further comprising a sensor for measuring energy of light reflected from said substrate in order to obtain energy incident on said projection optical system.
The apparatus according to any one of claims 0. 12. A projection exposure apparatus for scanning and exposing the substrate by moving the substrate in synchronization with the movement of the mask and projecting an image of the pattern of the mask onto the substrate, wherein: A projection optical system for projecting an image on the substrate, a first sensor for measuring the energy of illumination light passing through the projection optical system, and for measuring energy of light reflected by the substrate A second sensor, and an imaging state of a projection image of the pattern projected on the substrate during scanning exposure of the substrate based on the measurement result of the first sensor and the measurement result of the second sensor. A projection exposure apparatus, comprising: an adjusting unit that adjusts the distance. 13. A light source for emitting the illumination light, and a third sensor for measuring energy of the illumination light from the light source between the light source and the projection optical system; The output ratio of the sensor and the third sensor is determined in advance, and the adjusting unit adjusts the third ratio output during the scanning exposure.
The apparatus according to claim 12, wherein the imaging state is adjusted according to a measurement result of a sensor. 14. The adjusting means calculates energy incident on the projection optical system based on the output of the first sensor and the output of the second sensor, and calculates the energy of the projection image based on the calculation result. 14. The apparatus according to claim 12, wherein an imaging state is adjusted. 15. The adjustment means calculates a change in the imaging state of the projection image based on an output of the first sensor and an output of the second sensor, and calculates the change in the imaging state of the projection image based on the calculation result. 14. The apparatus according to claim 12, wherein the imaging state of the image is adjusted. 16. The image forming apparatus according to claim 8, wherein the adjusting unit adjusts the imaging state according to a position of the mask or the substrate during the scanning exposure. Equipment. 17. A projection exposure apparatus for scanning and exposing the substrate by moving the substrate in synchronization with the movement of the mask and projecting an image of the pattern of the mask onto the substrate, thereby scanning and exposing the substrate. Scanning means for moving the mask and the substrate in order to adjust the optical characteristics of the projection optical system, and for adjusting the image forming state of the pattern image during scanning exposure of the substrate. Control means for controlling the adjusting means; and a projection exposure apparatus. 18. The apparatus according to claim 18, further comprising a driving element for moving the mask to adjust an image forming state of the image of the pattern projected on the substrate, wherein the control unit controls the projected image of the pattern during the scanning exposure. 18. The apparatus according to claim 17, wherein the driving element is controlled to adjust an image forming state. 19. An interferometer for measuring positional information of the mask or the substrate during the scanning exposure, wherein the control means adjusts an image forming state of the pattern image in accordance with an output of the interferometer. The device according to claim 17, wherein the device is controlled. 20. A projection exposure apparatus for scanning and exposing the substrate by moving the substrate in synchronization with the movement of the mask in a predetermined direction and projecting an image of the pattern of the mask onto the substrate. A mask stage capable of holding and moving a mask, a substrate stage capable of holding and moving the substrate, and the mask and the projection optics when the mask stage holding the mask is moved in the predetermined direction. And a detector for detecting the intensity of the illumination light passing through the system. 21. An interferometer for measuring positional information of said mask stage in said predetermined direction, and storage means for storing the intensity of illumination light detected by said detector in association with the measurement result of said interferometer. The apparatus of claim 20, further comprising: 22. A light source for pulsating illumination light for exposing the substrate, wherein the detector detects the intensity of the illumination light every predetermined number of pulse oscillations. 22. The apparatus according to 20 or 21. 23. The apparatus according to claim 20, wherein said detector is provided on said substrate stage. 24. A light source for emitting illumination light for exposing the substrate, wherein the detector has a detection surface larger than an irradiation area of the illumination light passing through the projection optical system. Device according to any one of claims 20 to 23. 25. The method according to claim 20, wherein a transmittance of the mask corresponding to a position of the mask in the predetermined direction is obtained based on an output of the detector. apparatus. 26. An image forming apparatus according to claim 26, further comprising adjusting means for adjusting an image forming state of the pattern image during the scanning exposure according to the intensity detected by the detector prior to the scanning exposure of the substrate. The device according to any one of claims 20 to 25, characterized in that it is characterized in that: 27. A device manufacturing method, comprising a step of exposing the substrate using the pattern of the mask by using the apparatus according to claim 1. Description: 28. Scan exposure of the substrate by moving the substrate in synchronization with the movement of the mask in a predetermined direction and projecting an image of the pattern of the mask onto the substrate via a projection optical system. In an exposure method, prior to scanning exposure of the substrate, a change in incident energy to the projection optical system caused by moving the mask in the predetermined direction is obtained. 29. An imaging state of a projected image of the pattern is adjusted during the scanning exposure according to a change in incident energy to the projection optical system obtained prior to the scanning exposure. 29. The method according to claim 28. 30. Exposure for moving a substrate with respect to illumination light passing through a projection optical system in synchronization with movement of a mask in a predetermined direction with respect to illumination light, and scanning and exposing the substrate using the pattern of the mask. In the method, prior to the scanning exposure, a change characteristic of the transmittance of the mask in the irradiation area of the illumination light when the mask is moved in the predetermined direction with respect to the irradiation area of the illumination light is obtained. An exposure method comprising: 31. The method according to claim 30, wherein the transmittance change characteristic is stored in correspondence with a position of the mask in the predetermined direction. 32. The transmittance change characteristic is obtained by detecting a change in the intensity of illumination light passing through the projection optical system while moving the mask in the predetermined direction. 30. The method according to 30 or 31. 33. The method according to claim 30, wherein during the scanning exposure of the substrate, the exposure condition is adjusted based on the determined change characteristic of the transmittance. 34. An exposure method for exposing the substrate by projecting an image of a pattern of the mask onto a substrate via a projection optical system, wherein the mask is exposed to illumination light to scan and expose a front substrate. Moving the substrate in a predetermined direction with respect to the illumination light in synchronization with the movement of the mask; and projecting an image of a pattern projected through the projection optical system during scanning exposure of the substrate. An exposure method comprising adjusting a magnification. 35. The method according to claim 34, wherein during the scanning exposure, the relative speed between the mask and the substrate is adjusted according to the adjustment of the projection magnification. 36. The adjustment of the projection magnification is used to adjust a transfer magnification of a pattern of the mask transferred onto the substrate in a direction perpendicular to the predetermined direction, and the adjustment of the relative speed is performed on the substrate. 36. The method according to claim 34, wherein the method is used for adjusting a transfer magnification of the pattern of the mask transferred onto the mask in the predetermined direction. 37. An exposure method for exposing the substrate by projecting an image of a pattern of a mask onto the substrate, wherein the mask and the substrate are moved with respect to illumination light to scan and expose the substrate. Wherein, during the scanning exposure of the substrate, an image formation state of an image of a pattern formed on the substrate is adjusted according to a change in distribution of the pattern of the mask in an irradiation area of the illumination light. Exposure method. 38. The method according to claim 37, wherein the adjustment of the imaging state is performed according to the position of the mask during the scanning exposure. 39. An exposure method for scanning and exposing the substrate by synchronously moving the mask and the substrate and projecting an image of the pattern of the mask onto the substrate, wherein the substrate is moved in a predetermined direction. Scanning exposure, and scanning exposure for moving the substrate in a direction opposite to the predetermined direction can be performed, and adjustment of an image forming state of the image of the pattern formed on the substrate is performed on the substrate. An exposure method, wherein control is performed according to a moving direction. 40. The method according to claim 39, wherein the data used for adjusting the imaging state is stored according to the position of the mask or the substrate. 41. The method according to claim 40, wherein the data reading direction is switched according to the moving direction of the substrate. 42. A device manufacturing method, comprising a step of exposing the substrate to a pattern of the mask using the method according to any one of claims 28 to 41.